Environmental support of metallurgical plant construction project in the Subarctic Mountains (Trans-Baikal Territory)

The article analyzes the results of the environmental assessment of the construction site of the Udokan mining and metallurgical plant (MMP) in the Kalarsky district of the Trans-Baikal Territory. The Udokan deposit is the largest deposit in Russia with copper reserves of 20.1 million tons. The construction area is characterized by extreme natural conditions, natural complexes that are sensitive to anthropogenic impact. The results of the environmental impact assessment of the territory of the planned construction of the Udokan mining and metallurgical plant for the extraction and processing of copper are analyzed. The impact of the construction and the Udokan project on copper mining is assessed as significant. However, taking into account the observance of all technical and operational standards, it can be assessed as acceptable. Specialists of the Institute have developed and implemented a system of environmental monitoring of the impact of construction on the environment. A set of environmental measures to preserve the biodiversity of mountain subarctic ecosystems is proposed.

The missing pieces for better future predictions in subarctic ecosystems: A Torneträsk case study

Arctic and subarctic ecosystems are experiencing substantial changes in hydrology, vegetation, permafrost conditions, and carbon cycling, in response to climatic change and other anthropogenic drivers, and these changes are likely to continue over this century. The total magnitude of these changes results from multiple interactions among these drivers. Field measurements can address the overall responses to different changing drivers, but are less capable of quantifying the interactions among them. Currently, a comprehensive assessment of the drivers of ecosystem changes, and the magnitude of their direct and indirect impacts on subarctic ecosystems, is missing. The Torneträsk area, in the Swedish subarctic, has an unrivalled history of environmental observation over 100 years, and is one of the most studied sites in the Arctic. In this study, we summarize and rank the drivers of ecosystem change in the Torneträsk area, and propose research priorities identified, by expert assessment, to improve predictions of ecosystem changes. The research priorities identified include understanding impacts on ecosystems brought on by altered frequency and intensity of winter warming events, evapotranspiration rates, rainfall, duration of snow cover and lake-ice, changed soil moisture, and droughts. This case study can help us understand the ongoing ecosystem changes occurring in the Torneträsk area, and contribute to improve predictions of future ecosystem changes at a larger scale. This understanding will provide the basis for the future mitigation and adaptation plans needed in a changing climate.

The missing pieces for better future predictions in subarctic ecosystems

<p>Arctic and subarctic ecosystems are undergoing substantial changes in response to climatic and other anthropogenic drivers, and these changes are likely to continue over this Century. Due to the strong linkages between the biotic (vegetation and carbon cycle) and abiotic (permafrost, hydrology and local climate) ecosystem components, the total magnitude of these changes result from multiple interacting effects that can enhance or counter the direct effects. In some cases, short-lived extreme events can override climate-driven long-term trends. The field measurements can mostly tackle individual drivers rather than the interactions between them. Currently, a comprehensive assessment of the drivers of different changes and the magnitude of their impact on subarctic ecosystems is missing. The Torneträsk area, in the Swedish subarctic, has an unrivalled history of environmental observation over 100 years and encompasses the 12% of all published papers and the 19% of all study citations across the Arctic. In this study, we summarize and rank the direct and indirect drivers of ecosystem change in the Torneträsk area, and propose future research priorities identified to improve future predictions of ecosystem change. First, we identified the direct and indirect changing drivers and the multiple related processes and feedbacks impacting the local climate, permafrost, hydrology, vegetation, and the carbon cycle based on the existing literature. Subsequently, an Expert Elicitation with the participation of 27 leading scientists was used to rank the short- (2020-2040) and long-term (2040-2100) future impact of these drivers according to their opinions on the relative importance and novelty. These two key evaluation matrices form the basis for identifying the current research priorities for subarctic regions. The relatively small size of the Torneträsk area, its great biological and geomorphological complexity, and its unique datasets is a microcosm of the subarctic and the rapidly transforming Arctic ecosystems that can help understand the ongoing processes and future ecosystem changes at a larger circumpolar-scale. This in turn will provide the basis for future mitigation and adaptation plans needed in a changing climate.</p>

How does simulated climate change affect the susceptibility of SOM to priming by LMWOS in the Subarctic?

<p>Soil organic matter (SOM) stabilization plays an important role in long-term storage of carbon (C). However, now many ecosystems are experiencing global climate change, which could change soil C balance through affecting the C input via plant community shifts, and C losses via SOM decomposition. In subarctic ecosystems, plant community composition and productivity are shifting because of climate change. This change of above-ground communities will affect rhizosphere input such as low molecular weight organic substances (LMWOS), which can affect microbial decomposer activities and subsequent contribution to SOM mineralization (priming effect). In the present study, we simulated climate change with N fertilization, to represent a warming enhanced nutrient cycling, and litter input, to simulate arctic greening, to evaluate the effect of a changing climate on subarctic ecosystems in Abisko, Sweden. The 6 sampled field treatments included three years of chronic N addition (5 g N m<sup>-2</sup> y<sup>-1</sup>), three years of chronic litter addition (90 g m<sup>-2</sup> y<sup>-1</sup>), three years of chronic N and litter additions, one year of high N addition (15 g N m<sup>-2</sup> y<sup>-1</sup>), one year of high litter addition (270 g m<sup>-2</sup> y<sup>-1</sup>) and a control treatment. All treatments were established in 1×1 m experimental squares and had 6 replicates. We resolved effects on plant community (NDVI), SOM mineralization, microbial composition, bacterial and fungal growth rates, and soil properties.</p><p>We found that N treatments changed plant community and stimulated productivity and that the associated increase in belowground LMWOS induced shifts in the soil microbial community. This coincided with a tendency for a shift towards bacterial dominated decomposition (low fungi/bacterial growth ratio) and a microbial community that had shifted from gram-positive bacteria to gram-negative bacteria; a shift often observed when comparing bulk with rhizosphere conditions. However, N treatments had no effect on SOC mineralization, but did increase soil gross N mineralization. This shift in the C/N of mineralisation might be because N treatments accelerated the growth of fast growing plant species with higher nutrient content, whose litter input provided microbes with fresh OM richer in N.</p><p>These responses in belowground community and processes driven by rhizosphere input prompted the next question: how did the simulated climate change affect the susceptibility of SOM to priming by LMWOS? To assess this question and explore the microbial mechanisms underpinning priming of SOM mineralization, we added a factorial set of additions including <sup>13</sup>C-glucose with and without mineral N, and <sup>13</sup>C-alanine semicontinously to simulate the effect of belowground LMWOS input on SOM mineralization and microbial activity, and investigate how the SOM priming was linked to the actively growing microorganisms. Therefore, we incubated these samples for 7 days, treated with <sup>13</sup>C LMWOS, and measured SOC and SON mineralization to assess SOM priming, bacterial and fungal growth rates, microbial phospholipid fatty acids (PLFAs) and <sup>13</sup>C-PLFA enrichment, as well as the microbial C use efficiencies to assess microbial responses to LMWOS additions.</p>

Seasonal Responses of Terrestrial Carbon Cycle to Climate Variations in CMIP5 Models: Evaluation and Projection

Seventeen Earth system models (ESMs) from phase 5 of the Coupled Model Intercomparison Project (CMIP5) were evaluated, focusing on the seasonal sensitivities of net biome production (NBP), net primary production (NPP), and heterotrophic respiration (Rh) to interannual variations in temperature and precipitation during 1982–2005 and their changes over the twenty-first century. Temperature sensitivity of NPP in ESMs was generally consistent across northern high-latitude biomes but significantly more negative for tropical and subtropical biomes relative to satellite-derived estimates. The temperature sensitivity of NBP in both inversion-based and ESM estimates was generally consistent in March–May (MAM) and September–November (SON) for tropical forests, semiarid ecosystems, and boreal forests. By contrast, for inversion-based NBP estimates, temperature sensitivity of NBP was nonsignificant for June–August (JJA) for all biomes except boreal forest; whereas, for ESM NBP estimates, the temperature sensitivity for JJA was significantly negative for all biomes except shrublands and subarctic ecosystems. Both satellite-derived NPP and inversion-based NBP are often decoupled from precipitation, whereas ESM NPP and NBP estimates are generally positively correlated with precipitation, suggesting that ESMs are oversensitive to precipitation. Over the twenty-first century, changes in temperature sensitivities of NPP, Rh, and NBP are consistent across all RCPs but stronger under more intensive scenarios. The temperature sensitivity of NBP was found to decrease in tropics and subtropics and increase in northern high latitudes in MAM due to an increased temperature sensitivity of NPP. Across all biomes, projected temperature sensitivity of NPP decreased in JJA and SON. Projected precipitation sensitivity of NBP did not change across biomes, except over grasslands in MAM.

Mechanical site preparation and nurse plant facilitation for the restoration of subarctic forest ecosystems

Sustainable forest management implies successful regeneration following disturbances. Tree regeneration in subarctic ecosystems can, however, be constrained by limitations to seedling establishment related to cold soils, slow decomposition rates, and competition by ericaceous species. We established a field trial at the northern limit of commercial forests in Québec, Canada, to evaluate to what extent mechanical site preparation (MSP) and planting of a nurse N2-fixing species could promote conifer establishment on a site burned in 2007. The experiment comprised four treatments applied in 2010: standard MSP (disc trenching), standard MSP plus planting of Alnus crispa, intensive MSP, with larger furrows than standard MSP, and a control. Main plots were divided and planted in 2011 with Picea mariana (Mill.) Britton, Stearns & Poggenb. or Pinus banksiana Lamb. We monitored seedling survival, growth, nutrition, and microsite over a 3-year period. Results revealed interactions between treatments and planted species. Mechanical site preparation resulted in higher conifer growth relative to the control conditions, and planting Alnus resulted in growth gains similar to those obtained from intensive MSP. We measured competitive interactions between Alnus and the conifers that might eventually cancel out the initial benefits derived from facilitation by planting the nurse species. Longer term monitoring of interspecific interactions is needed to unravel the mechanisms responsible for the facilitative effect and identify the best management practices.